This invention relates to a disposable diaper adapted to absorb and contain body fluids discharged thereon.
As one example of disposable diapers, there has already been proposed a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets, and the diaper further includes a pair of side flaps lying outside transversely opposite side edges of the core and longitudinally of the diaper and a pair of leak-barrier cuffs lying in the vicinity of the transversely opposite side edges of the core and normally biased to rise on the inner surface of the diaper. Each of the side flaps is formed by the associated side edge portion of the backsheet lying transversely outside the associated side edge of the core and extending longitudinally of the diaper and the associated outer side edge portion of the cuff lying transversely outside its fixed side edge portion. In the side flap, the side edge portion of the topsheet terminates immediately outside the associated side edge of the core while the associated side edge portions of the backsheet and the cuff, respectively, extend transversely outward beyond the associated side edge portion of the topsheet. The disposable diaper of such type is disclosed, for example, in Japanese Patent Application Disclosure Nos. 1996-289902 and 1996-322876.
The side flaps and the leak-barrier cuffs surround a wearer""s legs and partially occupy a crotch region of the wearer being prone to excretion leak and stuffiness. To avoid these problems, it is desired to improve both the water resistance and the breathability of the side flaps and the cuffs.
If a plastic film is used as a stock material for the backsheet, a relatively high water resistance can be obtained but it is impossible to obtain a desired breathability. Even if the plastic film is processed to have fine pores, it is impossible to obtain a breathability sufficient to prevent the interior of the diaper from becoming stuffy.
In the case of the backsheet and the cuffs both formed by a nonwoven fabric, an effort to improve the water resistance by increasing the basis weight of the synthetic resin fiber forming the nonwoven fabric will result in increasing the fiber density in the nonwoven fabric and correspondingly deteriorate the breathability. On the contrary, an effort to improve the breathability by reducing the basis weight of the fiber forming the nonwoven fabric will reduce the fiber density in the nonwoven fabric and correspondingly deteriorate the water resistance.
It is an object of this invention to provide a disposable diaper provided with a pair of side flaps and a pair of leak-proof cuffs presenting optimized water pressure resistance and breathing resistance so that both a sufficiently high water resistance and a sufficiently high breathability can be ensured in the side flaps and the cuffs.
According to this invention, there is provided a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed therebetween, and formed with a pair of side flaps lying outside transversely opposite side edges of the core and extending longitudinally of the diaper, wherein: each of the side flaps is formed by a breathable and liquid-resistant first side sheet connected to the associated side edge portion of the topsheet lying in the vicinity of the associated side edge of the core and extending longitudinally of the diaper and at least one breathable and liquid-resistant second side sheet connected to the associated side edge portions of the top- and backsheets both lying in the vicinity of said associated side edge of the core or at least to the associated side edge portion of the backsheet and extending longitudinally of the diaper under the first side sheet wherein both the first and second side sheets have a water pressure resistance of 100xcx9c1500 mm and a breathing resistance of 0.03xcx9c0.8 Kpaxc2x7s/m.
With the disposable diaper according to this invention, each of the side flaps is formed by the first and second side sheets presenting a water pressure resistance of 100xcx9c1500 mm and a breathing resistance of 0.03xcx9c0.8 Kpaxc2x7s/m. Adjustment of these resistance values in such ranges, respectively, ensures the side flap to present a sufficiently high water pressure resistance as well as a sufficiently high breathability. As a result, leak of excretion otherwise occurring through the side flap can be reliably avoided and moisture generated within the diaper can be reliably breathed out to the exterior and thereby to avoid undesirable stuffiness otherwise generated within the diaper.
With the diaper 1 implemented to have the pair of leak-proof cuffs, it is ensured that these cuffs prevent a sufficiently high water pressure resistant as well as a sufficiently high breathability so far as the breathing resistance of the first side sheet is adjusted within a range of 0.03xcx9c0.8 Kpaxc2x7s/m. In this way, the diaper can prevent excretion discharged thereon from leaking through the cuffs and breath out moisture to the exterior through the cuffs to avoid undesirable stiffness otherwise generated within the diaper. Furthermore, adjustment of the water pressure resistance of the first side sheet to be higher than that of the second side sheet(s) effectively prevent exudation of excretion otherwise occurring through the first side sheet toward the second sheet(s).
The side flap comprising the first side sheet and two or more second side sheets is more effective than the side flap comprising the first side sheet and a single side sheet to improve its water pressure resistance and the diaper including such side flap is suitable particularly as the diaper exclusively used by adult discharging a relatively large amount of excretion.